1. Field of the Invention:
This invention relates to a novel 8-piperazinyl-1,7-naphthyridine derivative and more particularly, to a 8-piperazinyl-1,7-naphthyridine derivative useful as a medicine.
2. Description of the Background:
A number of 1,7-naphthyridine derivatives are known in the art. Among them, those having a medicinal effects are the one having an antihypertensive effect (U.S. Pat. No. 4,176,183) and the one having an insecticidal effect (Federal Republic of Germany Patent Application Laid-open No. 2,361,438). There is no other 1,7-naphthyridine derivative reported in the art which has any medicinal effect.
In these circumstances, the inventors had synthesized various 1,7-naphthyridine derivatives and detected their medicinal effects, and found that specific 1,7-naphthyridine derivatives have an excellent medicinal effect. A patent was applied based on such a finding (Japanese Patent Application No. 67,875/1986).